Revealing Mysteries of Hall Experiments on a-Si:H and a-SiC:H

Hall experiments performed on intrinsic, phosphorus and boron doped a-Si:H and a-SiC:H in the temperature regime 200 K ≤ T ≤400 K are introduced and discussed. The data confirm the double sign anomaly meaning the Hall coefficient is p-type on intrinsic and phosphorus doped a-Si:H and a-SiC:H, and n-type on boron doped a-Si:H. The Hall mobilities, μH, are significantly smaller than the drift mobilities, decreasing with increasing doping and/or carbon content. μH of holes is about half that for electron which indicate that μH scales approximately with 1/Eg where Eg is the tail slope. The presented interpretation of the Hall coefficient, that is introduced to be a function of Hall- and drift-mobility, enables the accurate determination of the carrier density in intrinsic and doped amorphous silicon and alloys from Hall data.